this is commission for
phew, pretty big one XD took me a while
The fall of the Black Beast is majorly influenced by the Luca Blight battle, first off. Also, the Black Beast is just a title, he's not an actual beast.
The Black Beast is an uncontrollable beast, always following his own desires. Upon the announcement of a seer's execution, the Black Beast went to stop it. However, because this would get in the way of the main villain's plans, manipulated the knights to slay the Beast and claim his title. The first round is against the soldiers that were formerly under his command. Braving the knights, the Beast encountered the seer.
Reize, Ivo, and Lily were enroute to stop the execution as well. When they arrived, the Black Beast lost his temper and sought to kill Reize and his friends. The second fight, however, left the Black Beast on the verge of death. It was a demon that offered a hand to the Black Beast in exchange for his servitude.
To the demon and everyone's surprise, the Black Beast stood on his own will while rejecting any help. Both Lily and Ivo were left incapitated, allowing the Black Beast to focus on the one person that he hates the most: Reize Seatlan.
With Reize's boomerangs broken, Ivo tosses Reize his sword to use in battle.
First Round: "The Chase" - Suikoden II
Second Round: "Dismiss" - Kingdom Hearts: Birth by Sleep
Reize vs The Black Beast (Final): "Dios Meltia" - Narikiri Dungeon X / "It has to be this way" - Metal Gear Rising: Revengeance